Sodium-potassium pump

The sodium-potassium pump is a membrane protein that uses ATP to move three sodium ions out of a cell and two potassium ions in. This unequal exchange helps maintain ion gradients and the cell’s electrical potential.

P-type ATPase: A family of membrane enzymes that transport ions by forming a phosphorylated intermediate. The sodium-potassium pump is a P-type ATPase that transiently phosphorylates itself during transport.
Electrochemical gradient: The combined effect of an ion’s concentration difference and electrical potential across a membrane. The pump builds gradients that store energy for transport and electrical signaling.
Action potential: A rapid, temporary change in membrane voltage that propagates along an excitable cell. The pump restores sodium and potassium gradients used during repeated action potentials.
Jens Christian Skou: A Danish biophysicist who discovered the sodium-potassium-activated ATPase in 1957. His biochemical work identified the enzyme responsible for coupled sodium and potassium transport.
Post-Albers cycle: A sequence of conformational states describing ion binding, phosphorylation, and release by the sodium-potassium pump. It details the pump’s alternating access and explains why sodium and potassium move in opposite directions.
Membrane potential: The voltage difference between the inside and outside of a cell membrane. The pump’s unequal charge exchange contributes directly to membrane voltage.
Secondary active transport: Transport that uses an ion gradient to drive another substance across a membrane without directly hydrolyzing ATP. The sodium gradient created by the pump drives many coupled uptake systems.
Nobel Prize in Chemistry: An annual international award recognizing outstanding contributions to chemistry. Skou received the 1997 prize for discovering the sodium-potassium pump.
ATP hydrolysis: The chemical breakdown of ATP into ADP and inorganic phosphate, releasing usable free energy. ATP hydrolysis powers the conformational changes that move ions against their gradients.
Sodium gradient: The difference in sodium concentration across a cell membrane, typically with more sodium outside animal cells. The pump maintains this gradient by exporting sodium from the cytoplasm.

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